The present invention relates to a test paper for use in the determintion of the concentration of common salt contained in urine and food for the purpose of personal health management, as well as the content of halogen ions such as bromine and iodine ions contained in water or soil for the inspection thereof, and further to a process for manufacturing such a paper and the use of the same.
Most of methods for determining the content of a halogen ion such as chloride ion, which are conventionally known, use silver or mercuric nitrate solution, and involves subjecting the silver or mercuric nitrate solution to the reaction with a sample of halogen-containing solution to produce water-insoluble silver or mercuric chloride. Recently, a chloride meter has been developed as a simple measuring instrument utilizing a coulometric titration. However, the conventional determining methods utilizing the precipitation of metal chlorides are accompanied by a problem in environmental pollution because of the toxicity of metal ions employed such as silver, mercury and the like. In addition, the conventional methods utilizing a coulometric titration require an expensive apparatus and hence, are generally not suitable.